Add MatterIndexPipeline

### Feature Description

_A clear and concise description of the feature you're requesting._

Add matter index pipeline to stored indexed terms for matters.

### Use Case

_Please provide a use case to help us understand your request in context._

Search for matters based off of a plain text search query.

### Solution

_Please describe your ideal solution._

Similar to event index pipeline but instead of parsing the transcript parse the matter document text and link to `matter_ref` instead of `event_ref`.

### Alternatives

_Please describe any alternatives you've considered, even if you've dismissed them._